1. Field of the Invention
The present invention relates to a method of inspecting a leakage current characteristic of a dielectric layer and an apparatus for performing the method. More particularly, the present invention relates to a method of inspecting a leakage current characteristic of a dielectric layer on a semiconductor substrate using corona ion charges, and an apparatus for inspecting a leakage current characteristic of a dielectric layer using the method.
2. Description of the Related Art
Recently, as semiconductor devices have become highly integrated and have also been operating at higher speeds, areas of memory cell regions in the semiconductor devices have been reduced. Thus, areas of regions in which a transistor and a capacitor in which each of the cells are formed have been reduced. In such highly integrated semiconductor devices, characteristics of a dielectric layer, e.g., a breakdown voltage characteristic, a leakage current characteristic, etc., deteriorate due to the reduction in area of a memory cell region.
In particular, the leakage current characteristic of the dielectric layer is deteriorated by contaminants at an interface between the dielectric layer and a semiconductor substrate. Also, the leakage current characteristic of the dielectric layer varies in accordance with step coverage of a patterned structure on the semiconductor substrate.
There are several conventional methods of inspecting a leakage current characteristic of a dielectric layer. One method measures a leakage current of a PN junction using a corona charger and a Kelvin probe. Another method measures a surface voltage using a Kelvin probe in which impurities on a semiconductor substrate having an interface between the semiconductor substrate and a dielectric layer are recognized. Still another method measures a stress-induced leakage current (SILC) and a gate dielectric integrity or gate oxide integrity (GOI) using a corona discharge.
In the above-mentioned conventional methods, after a dielectric layer is formed on a sample semiconductor substrate, a leakage current characteristic of the dielectric layer is inspected. A leakage current characteristic of a dielectric layer on a patterned semiconductor substrate is not determined based on the leakage current characteristic of the dielectric layer on the sample semiconductor substrate. That is, it is difficult to measure the leakage current characteristic of the dielectric layer on the patterned semiconductor substrate due to the step coverage of the dielectric layer on the patterned semiconductor substrate.
Also, since an area of a measurement region is large, characteristics of the dielectric layer are not minutely managed. For example, measuring the leakage current of the dielectric layer is performed on dies of the semiconductor substrate. Thus, the ability to accurately measure the leakage current of the dielectric layer with respect to various regions in each of the dies is needed.